Pipe-mold coatings



\ Patented Nov. 17, 1925.

UNITED STATES PATENT OFFICE.

' No Drawing.

DANIEL H. MELOCHE, 0F DETROIT, MICHIGAN, ASSIGNOR TO EARL HOLLEY, OF

I DETROIT, MICHIGAN.

R PIPE-MOLD coarmos.

molten cast iron is poured in against the rotating surface. By reason of the sudden shock of the entering metal, which neces sarily must be quite hot (over 2200 F.),

the surface of these steel molds is cracked and thus destroyed after 1,000 or 2,000 castings' have been made. These molds are sufficiently expensive so that the mold cost per casting is quite considerable. It is the object of this invention to reduce the moldcost by increasing the life of the molds.

The method is brieflyias follows The mold surface is first of all roughened by means of a' sand blast which is directed against the inner wall of the mold through a flexible hose, the molds being rotated as theflexible hose and sand blast nozzle is directed against the inner wall of the rotatr ing mold. The nozzle is slowly withdrawn so that every portion of the walls of the mold is treated. The surface of the mold,

having been thus roughened by the sand blast, heat is applied to the outer wall of the mold until the temperature of the mold exceeds 400 F. A wash is then prepared containing a relatively small quantity of sodium sillcate in solution and a relatively large quantity of fire clay in suspension.

The actual proportions used are as follows:

Five parts, by weight, f grade; n

, sodium silicate (containing 16.88%, by

weight, of sodium oxide, 35.80% of silica, and 46.88% of water) are dissolved in seventy parts, by weight, of water, and into this dilute solution twenty-five parts, by weight, of powdered fire clay are stirred.

These particular proportionsbein those disclosed in my coending a pllcation, Serial No. 1,581, filed anuary 10t 1925;

A mop or large brush is placed in this solution and the inside surface of the heated Application filed February 24, 1925. Serial No. 11,369.

thin coating of fire clay adheres to the wall of the mold. The heating of the mold is continued so that the ten'iperature is maintained despite the cooling effect of the wash, and the molds are repeatedly swabbed with the mop. By thus repeatedly heating the molds and applying the wash with the mop a coating of some thousandths of an inch in thickness is applied, the desired thickness being approximately .016" or 1/64".

Finally, the coating is polished with powdered graphite by means ofsteel wool or hard wood rollers, which are caused to traverse the full length of the rotating molds. From time to time, though not between each casting, it is necessary to apply more coating by means of the wash, the temperature of the molds being always raised above 400 F. for the purpose of instantaneously evaporating the water which serves as merely the carrier for the fire clay and binder.

The, chilling eifect of the metal mold is reduced by means of my coating, and it can still furtherbe reduced by the use of a superimposed coating of lampblack applied by a smoky flame, preferably of acetylene, which will be burnt with an insufficient amount of air inside the rotating mold. By adjusting the flame the period during which the metal remains molten in the mold can be regulated.

lVhat "I claim is 1. The method of protecting a rotatin cylindrical mold, consisting in first san blasting the wall of the mold, then heating the mold well above the boilin point of water, then brushing the roug ened and heated surface with a wash containing a little sodium silicate in solution and a considerable quantit of fire clay in suspension.

2..The metho of protecting a rotatin cylindrical mold, consisting irifirst san blasting the wall of the mold, then heating the mold well above the boiling point of water, then brushing the roughened and heated surface with a wash containing approxi mately five parts, by weight, of C grade sodium silicate in solution in approximately seventy parts, by weight, of water, and twenty-five parts, by weight, of powdered fireclayin suspension. 3. The method of protecting a rotatin cylindrical mold, consisting in first san mold swabbed with the mop, whereby a blasting the wall of the mold, then heating 0 the mold. well above the boilin point of water, then brushing the roug ened and heated surface with 1.11 washcontaining a little sodium silicate in solution and a con- 5 siderable quantity of fire clay in suspension, then pohshing the fire clay surface thus formed with aphite.

4. The -met 0d of protecting a rotating cylindrical mold, consisting in first sand 10 blasting the wall of the mold, then heating the mold well above the boilin point of water, then brushing the roug ened and heated surface with a wash containing a little sodium silicate in' solution and a considerable quantity of fire clay in suspension, 15 then smoking t e fire clay surface thus formed, whereby the freezing period of the molten metal will be prolonged.

In testimony whereof I aflix my signature.

DANIEL H. MELOCI-IE. 

